Are climbers able to breathe at high altitudes?
The higher you climb, the thinner the air becomes, until there is not enough oxygen to support life. On the highest mountains, there is just about enough oxygen for life to survive for a short time. Extremely fit mountaineers have managed to climb to the top of Mount Everest without the use of oxygen cylinders.
Our bodies can adapt slowly to a lack of oxygen, which is why expeditions to the Himalayas and other high ranges camp at progressively higher levels to get used to the thinner air. People living at high altitudes in the Andes and the Himalayas develop enlarged chests and changes in their lungs to help them breathe.
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What is chalk?
Chalk is formed from the skeletons of millions and millions of tiny animals called foraminifera. It is a sedimentary rock that formed millions of years ago beneath shallow seas. Chalk is used in the manufacture of rubber goods and paint.
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